Bibcode
Joulin, V.; Buchlin, E.; Solomon, J.; Guennou, C.
Bibliographical reference
Astronomy and Astrophysics, Volume 591, id.A148, 16 pp.
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7
2016
Journal
Citations
23
Refereed citations
22
Description
Context. To explain the high temperature of the corona, much attention
has been paid to the distribution of energy in dissipation events.
Indeed, if the event energy distribution is steep enough, the smallest,
unobservable events could be the largest contributors to the total
energy dissipation in the corona. Previous observations have shown a
wide distribution of energies but remain inconclusive about the precise
slope. Furthermore, these results rely on a very crude estimate of the
energy. On the other hand, more detailed spectroscopic studies of
structures such as coronal bright points do not provide enough
statistical information to derive their total contribution to heating.
Aims: We aim at getting a better estimate of the distributions of
the energy dissipated in coronal heating events using high-resolution,
multi-channel extreme ultraviolet (EUV) data. Methods: To
estimate the energies corresponding to heating events and deduce their
distribution, we detected brightenings in five EUV channels of the
Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics
Observatory (SDO). We combined the results of these detections and used
maps of temperature and emission measure derived from the same
observations to compute the energies. Results: We obtain
distributions of areas, durations, intensities, and energies (thermal,
radiative, and conductive) of events. These distributions are power laws
and we also find power-law correlations between event parameters.
Conclusions: The energy distributions indicate that the energy from a
population of events like the ones we detect represents a small
contribution to the total coronal heating, even when extrapolating to
smaller scales. The main explanations for this are how heating events
can be extracted from observational data, and the incomplete knowledge
of the thermal structure and processes in the coronal plasma attainable
from available observations.
Two movies attached to Fig. 3 are available in electronic form at http://www.aanda.org